function startMove(obj,attr,final,fn){

	clearInterval(obj.timer);

	obj.timer = setInterval(function(){
		//1.取得当前值
		iCur = 0;
		if(attr == "opacity"){
			iCur = Math.round(parseFloat(getStyle(obj,attr))*100);
		}else{
			iCur = parseInt(getStyle(obj,attr));
		}

		//2.计算速度
		var speed = (final - iCur)/10;
		speed = speed > 0 ? Math.ceil(speed):Math.floor(speed); 

		//3.检测停止
		if(parseInt(obj.style[attr]) == final){
			clearInterval(obj.timer);
			if(fn){
				fn();
			}
		}else{
			if(attr == "opacity"){
				// obj.style.filter = 'alpha:(opacity:'+(iCur + speed)+')';
				obj.style[attr] = (iCur + speed)/100;
			}else{
				obj.style[attr] = iCur + speed + "px";   
			}
		}
	},30)
}

function getStyle(obj,attr){
	if(obj.currentStyle){
		return obj.currentStyle[attr];
	}else{
		return getComputedStyle(obj,false)[attr];
	}
}



